1. Field of the Invention
The present invention relates generally to a method of forming IC packages in which a number of semiconductor chips are mounted on a substrate.
2. Related Background Art
When a number of semiconductor chips are mounted on a substrate 21 and are covered with a resin 25 to be protected, which then is divided into individual semiconductor packages, conventionally, the substrate warps due to the resin which is adhered onto only one side of the substrate as shown in FIG. 2.
As shown in FIG. 2, since the resin 25 is allowed to adhere onto only one side of the substrate, the substrate warps to one side. Hence, in the steps thereafter, it is necessary to work with consideration given to this warp. For instance, sufficient space should be provided so as to prevent upper-side and lower-side substrates from coming to contact with each other when a substrate is to be mounted on a magazine, or the focus of a microscope should be readjusted continuously in inspecting a substrate, which has required extra time and energy. In addition, when a substrate is cut and thereby semiconductor packages are obtained, such warp should be taken into account and the substrate cannot be cut with high precision.
In order to solve the above-mentioned problems, in the present invention, when semiconductor chips mounted on a substrate are to be covered with resin, resin is also allowed to adhere onto the opposite side of the substrate on which the semiconductor chips are mounted. According to this, comparable levels of resin stress are exerted on respective sides of the substrate. Hence, the stresses exerted on the respective sides cancel each other out and thus the substrate does not warp. The resin that has adhered onto the opposite side of the substrate on which the semiconductor chips are mounted is removed before the substrate is cut.